FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
As amended by the Patents (Amendment) Act, 2005
&
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2006
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
A Jack for removing a dowel pin
APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company


_j INVENTOR
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2 Pandit Ashok Rabhaji of LT Motor Division, Crompton Greaves Ltd, A-6/2 MIDC,
Ahmednagar-414111, Maharashtra, India, Indian National

PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the nature of this invention and the manner in which it is to be performed:


FIELD OF INVENTION
This invention relates to a jack for removing a dowel pin and more particularly to a jack for removing a tapped dowel pin holding a stator assembly together.
BACKGROUND
In the field of power systems and industrial electronics, electrical rotating machines like motors or alternators usually comprises of a stator assembly and a rotor assembly. The stator assembly comprises of a stator body and a stator pack. The stator pack is firmly held within the stator body without any axial or radial movement. Typically, dowel pins are used to hold the stator pack within the stator body. After the stator pack is pressed into the stator body, holes to accommodate the dowel pins are drilled through the stator body and into the stator pack at pre-determined positions on the stator body. The dowel pins are then pushed into the drilled hole using a mallet, hammer or any other suitable tool such that no portions of the dowel pins protrude outside the stator body. Such an arrangement prevents any radial or axial movement of the stator pack within the stator body during the operation or transportation of the assembly.
The stator pack is required to be disengaged from the stator body in the event of either or both of them being damaged or requiring repair. In such a scenario, removal of dowel pins becomes essential. Conventionally, to remove dowel pins from a stator body, a hole bigger than the diameter of the dowel pins is first made on the stator body around each of the dowel pins. The dowel pins are then destroyed by drilling them out. This will invariably damage both the stator body and the stator pack. Alternatively, the dowel pins
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are either driven out or pushed out. Such removal of dowel pins is difficult, time consuming and increases the downtime of the machines like motors or alternators.
OBJECTS OF THE INVENTION
An object of the invention is to provide a jack to remove a tapped dowel pin from a stator assembly without damaging any component of the stator assembly or the dowel pin.
Another object of the invention is to provide a jack which is cheap, manually operated without any power supply, easy to use and facilitates a quick and easy removal of the dowel pin thereby reducing the down time of the machine.
DETAILED DESCRIPTION OF THE INVENTION
In order to achieve the aforesaid and other objectives, according to the invention, a jack is provided for removing a tapped dowel pin holding a stator assembly together. The jack comprises of a structure having a horizontal flat portion formed with an engaging hole and at least two legs extending downwardly from the horizontal flat portion. Further, a screw with a locking nut in thread engagement therewith is inserted through the engaging hole such that the locking nut remains disposed above the horizontal flat portion.
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These and other aspects, features and advantages of the invention will be better understood with reference to the following detailed description, accompanying drawings and appended claims, in which,
Fig 1 illustrates a cross sectional view of a tapped dowel pin holding a stator assembly together.
Fig 2 illustrates a cross sectional view of a jack for removing a tapped dowel pin holding a stator assembly together.
Fig 3a, Fig 3b and Fig 3c are cross sectional views of a jack located on a stator assembly, each figure depicting steps involved in removing a tapped dowel pin from a stator assembly.
Fig 1 illustrates a cross sectional view of a tapped dowel pin 1 holding a stator assembly together. The stator assembly of a motor comprises of a stator body 2 and a stator pack 3. The stator pack 3 is held firmly within the stator body 2 by means of a dowel pin 1 so as to prevent any axial or radial movement of it within the stator body 2. During the assembly stage of the stator body 2 and stator pack 3, provisions (holes) are made on the stator body 2 and stator pack 3 to accommodate dowel pins 1. Dowel pins 1 are then pushed into the holes such that no portions of the dowel pins 1 protrude outside the stator body 2. Such an arrangement holds the stator body 2 and the stator pack 3 firmly, thereby preventing any axial or radial movement of the stator pack 3 in the stator body 2 during operation or transportation of the stator assembly.
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Fig 2 depicts a cross sectional view of a jack for removing a tapped dowel pin 1 holding a stator assembly together. The jack for removing the tapped dowel pin 1 is a C-shaped structure having a horizontal flat portion 4 and two legs (7 & 8) at opposite ends (5 & 6). The legs (7 & 8) extend downwardly from the opposite ends (5 & 6) to as to elevate and support the horizontal flat portion 4. An engaging hole is provided on the horizontal flat portion so as to allow a screw 9 to pass through it. The screw 9 is in thread engagement with a locking nut 10 such that the locking nut 10 remains disposed above the horizontal flat portion 4.
Fig 3a, Fig 3b and Fig 3c illustrate cross sectional views of a jack located on a stator assembly wherein each figure depicts a step involved in removing a tapped dowel pin 1 holding a stator assembly together. Fig 3a shows the jack located on a stator body of the stator assembly for removing a tapped dowel pin 1 holding a stator assembly together. The jack is placed on the stator body 2 in such a manner that the engaging hole on a horizontal flat portion 4 of the jack is aligned with the tapped dowel pin 1. A screw 9 is extended through the engaging hole towards the tapped dowel pin 1. A locking nut 10 is provided in thread engagement with the screw 9 such that the locking nut 10 remains disposed above the horizontal flat portion 4 at all times. The screw 9 is then rotated in a clockwise direction to engage the tapped dowel pin 1 with it. The locking nut 10 is adjusted by rotating it up or down along the length of the screw 9 so as to allow the screw 9 to be completely engaged with the dowel pin 1. Fig 3b depicts the screw 9 in thread engagement with the tapped dowel pin 1 holding the stator assembly together. Fig 3c depicts the next subsequent step for removing the tapped dowel pin 1. After the screw 9
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is engaged with the tapped dowel pin 1, locking nut 10 is rotated to move it downwardly with the help of a spanner, wrench or any other suitable tool Any further downwardly movement of the locking nut 10 is prevented as soon as the locking nut 10 comes in contact with the horizontal flat portion 4. However, further rotation of the locking nut 10 to move it downwardly, pushes the screw 9 upwards since the locking nut 10 cannot move down. Since the tapped dowel pin 1 is in thread engagement with the screw 9, upward motion of the screw 9 forces the tapped dowel pin 1 to move up along with the screw 9, thereby disengaging itself from the stator assembly without any damage to either the stator assembly or itself.
According to the invention, the jack enables an easy removal of dowel pins 1 holding a stator assembly together without any damage to the stator body 2, stator pack 3 of the stator assembly or the dowel pins. Owing to a simple mechanical design, the jack is hand held, easy to use, operates without any power supply and is cheap to manufacture.
The configuration of the jack may vary. Instead of a horizontal flat portion 4 as depicted in the present embodiment, there can be a circular surface or a surface of some other shape. Instead of two legs (7 & 8) extending from the horizontal flat portion 4, there can be more than two legs depending on the shape of the flat portion to balance the jack properly.
Although the invention has been described with reference to a specific embodiment, this description is not meant to be construed in a limiting sense. Various
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modifications of the disclosed embodiment, as well as alternate embodiments of the invention, will become apparent to persons skilled in the art upon reference to the description of the invention. It is therefore contemplated that such modifications can be made without departing from the spirit or scope of the invention as defined.
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1. A jack for removing a tapped dowel pin holding a stator assembly together,
said jack comprising a structure having a flat portion formed with an engaging
hole and at least two legs extending downwardly from said flat portion; a
screw extending through said engaging hole and a locking nut in thread
engagement with said screw and disposed above said flat portion.
2. A jack as claimed in claim I, wherein said structure is C-shaped.
3. A jack as claimed in claim 1 or 2, wherein said screw is provided with a head.
4. A jack as claimed in claim 3, wherein said head is hexagonal shaped.
Dated this 14th day of August 2008

(Prita Madan)
ofKhaitan&Co
Agent for the Applicants